1. Field of the Invention
This invention relates to a foldable mechanism, and more specifically to a foldable mechanism for a base of a playyard.
2. Description of Related Arts
A wide variety of playyards, which are also referred to as playpens, have been designed, developed, and commercialized for many years. In city life, the living space is crowded. If a playyard can not be stored in a small size, it will be troublesome. For solving the storage problem, playyards are usually designed to be foldable for storage.
In U.S. Pat. No. 5,819,342, disclosed is a foldable playyard with a latch locking hub system, comprising a lower frame assembly including a hub and a plurality of hub legs, an upper frame assembly comprising a plurality of side rail units, and corner legs. In view of FIG. 2 of the US ""342 patent (FIG. 1 in the specification), it is clear that the hub unit of the US patent is constructed by a plurality of complicated elements, and thus its structure is complicated and the manufacturing cost thereof is higher.
Further, in U.S. Pat. No. 6,259,667, disclosed is a lower frame structure of a foldable playyard comprising a hub being operable to lock the lower frame structure at an erected state and to unlock the lower frame structure to allow it to collapse to a collapsed state; four hub legs, one end portion of each of the hub legs being pivotally coupled to the hub such that the hub legs are capable of pivotal movement in a longitudinal direction of the hub between an erected position and a collapsed position; and a first L-shaped auxiliary supporting tube pivotally coupled to a first hub leg at a coupling end thereof and a second auxiliary supporting tube pivotally coupled to a third hub leg at a coupling end thereof and arranged such that the auxiliary supporting tubes may pivot in a direction parallel to the axial direction of the hub leg. From FIG. 2 of the patent (FIG. 2 of the specification), it is found that the hub is also constructed by a plurality of elements, which again will raise the manufacturing cost of the playyard.
In the prior art references cited above, the foldable structure for the base of the playyard uses many parts, which not only complicate the structure but also increase the cost thereof.
In view of the sharp increase in the business of playyard fields, designing less complicated structures for the foldable mechanism of the base of the playyard has become of paramount importance.
The invention is aimed at overcoming the problems existing in the prior art.
It is, therefore, an object of the invention to provide a foldable mechanism for the base of playyard, which can simplify the structure of the foldable mechanism and reduce the number of parts used therein.
To accomplish the above objects, according to the invention, there is provided a foldable mechanism for a base of a playyard comprising: a center seat pivotally connected with a plurality of bars with pins; a stationary block having horizontal grooves and being fixed in the center seat; a movable block having inclined grooves; movable pins penetrating the horizontal grooves of the stationary block and inclined grooves of the movable block so as to restrict the pivotal movement of the bars; and a resilient element being positioned between the stationary block and the movable block.
When the movable block is pulled up, the movable pins in the inclined grooves of the movable block move toward the center of the seat, so that restriction of the pivotal rotation of the bars by the movable pins is removed. The bars are rotating vertically, the seat of the playyard is collapsed, and then the movable pins move back to the original positions by the recovery force of the resilient element, while the center seat is pressed. The movable pins in the inclined grooves of the movable block again move toward the center of the seat, the bars are rotating horizontally, and then the movable pins move back to the original positions, so that pivotal rotation of the bars is again restricted by the movable pins.
The foldable mechanism, further comprises a webbing passing through the movable block so as to pull the movable block with the webbing. With the provision of the webbing, users may fold the foldable mechanism easier.
In the foldable mechanism, the movable block is provided with vertical grooves, and stationary pins for fixing the stationary block with respect to the center seat and which penetrates through the vertical grooves, such that the movable block will move vertically.
In the foldable mechanism, the resilient element is preferably a spring.
Additional features of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the disclosed specific embodiment may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.